The treatment of breast cancer depends on the individual circumstances (or stage), such as the rate of growth, the size of the tumour, and whether or not it has spread. (See "Staging: How bad is the breast cancer?") Treatment options for breast cancer include surgery, radiation therapy, chemotherapy, and medication therapy (including hormone and biological therapy). There are many, many available options and combinations for treatment, and treatment is becoming more successful than ever. The 5-year survival rate for women diagnosed with breast cancer is 88%.

Surgery

With surgery, either part or all of the breast tissue is removed. If only the tumour and some surrounding tissue are removed, it is called a lumpectomy, or a partial mastectomy if a larger area of the breast is removed. A mastectomy involves removing the whole breast, and sometimes the lymph nodes in the underarms may also be taken out. Breast reconstruction surgery may be an option for many women either at the time of surgery or at a later date.

The source of the hormones that stimulate growth - ovaries or the adrenal gland - may also be surgically removed.

Radiation

Radiation therapy is often administered after lumpectomy or partial mastectomy. Radiation kills cancer cells in the breast and sometimes in the armpit and chest wall as well. Side effects of radiation therapy such as skin redness and tiredness are the result of healthy tissue in the area being destroyed. These effects go away on their own following the completion of therapy.

Chemotherapy

While successful surgery and radiation therapy rely on exact knowledge of where the tumour is located, systemic therapy does not. Chemotherapy involves taking medications to destroy cancer cells in various parts of the body. Hormone therapy works on cancerous cells that have estrogen receptors, making them susceptible to estrogen-blocking medications.

Chemotherapy usually involves a combination of medications, some taken by mouth and some given by injection. There are many types of chemotherapy combinations or regimens that are given for breast cancer. Chemotherapy interferes with the growth of cancer cells, but it also affects healthy cells. Common side effects of chemotherapy can include nausea, vomiting, hair loss, and infection.

Hormonal therapy (e.g., tamoxifen [Nolvadex® and generics], letrozole [Femara®], or anastrazole [Arimidex®]) also helps stop the growth of cancer cells and may be used for up to 5 years for postmenopausal women who have receptor-positive cancer. Common side effects of hormonal therapy include hot flashes and irregular menstruation.

Biological therapy (e.g., trastuzumab [Herceptin®]) interferes with the growth of cancer cells and helps the body to kill cancers cells. This treatment targets the breast cancer cells only and is generally considered less toxic than traditional chemotherapy. It is usually used for breast cancer that has too much of a protein called HER2. Biological therapy is associated with side effects such as fever, chills, and headache.